The problem I was initially trying to solve is explained in this post.
tl;dr: multilingual website, redirecting to translated .cshtml views depending on the language.
Azure was treating the view re-routing differently in the case of Home/Index, so I made patch to solve that (see own-answer in previous post).
Current problem: I thought it was solved, but it was just because the css was cached. Now it is a mess, that is to say: the routing of the css elements seems to have changed after deploying to Azure. Again: this can not be reproduced in localhost.
Anybody has any idea about how to deal with this seemingly undebuggable differences between localhost tests and Azure?